The present invention relates to ovens for heating food products, and more particularly to an oven which circulates hot air through food products which are held in a perforate rotating container.
A very popular form of cooked potatoes is what is commonly known as "french fries". It is estimated that in North America alone, there are sixteen billion servings of french fries consumed annually. The common method of cooking french fries is to cut the potatoes into elongate pieces, having a generally square cross-sectional configuration of about 1/4 to 1/2 inch in diameter. (There are also other forms, such as forming rounded pieces of mashed potatoes.) The potato pieces are then placed in a wire basket and lowered into a high temperature cooking oil to cook the potatoes with a crisp fried surface.
One of the problems of cooking french fries in this manner in a restaurant is that a reservoir of high temperature oil must be maintained for long periods of time. There are some elements of danger in maintaining this hot oil. First, the oil sometimes splatters on a person's skin, causing serious burns. Also, maintaining this high temperature oil can itself be a fire hazzard, and the oil must be changed (or at least should be changed) with reasonable frequency. Further, the fumes which are emitted from this cooking oil must be vented to outside atmosphere, and this requires extra equipment. Another consideration is that with increasing emphasis on low fat diets, deep frying in oil is for some people quite undesirable.
Another method of cooking french fries is to simply lay the potato pieces on a pan and heat these in a conventional oven. However, the unexposed surfaces of the potato pieces (i.e., the surfaces which rest against the pan or those which are positioned one against the other) are not directly in contact with the hot air, with the result that the entire surface of each piece is not cooked with a uniform crispness. One solution to this problem would be to open the oven at periodic intervals and move the potato pieces to different positions on the pan. However, in a restaurant operation, this constant opening and closing of the oven would be impractical.
Another approach to the cooking of french fried potatoes without immersing them in oil is shown in two U.S. patents, U.S. Pat. Nos. 4,155,294 and 4,259,419. In these patents, there is shown a perforate food container which has a square cross sectional configuration and which is mounted for rotation in an oven chamber. Hot air is blown toward the food container to heat the potato pieces or other food products in the container. As the container is slowly rotated in the chamber, the food pieces change position relative to one another so that the surfaces of the food pieces are cooked with greater uniformity.
While the apparatus shown in these two U.S. patents is an advance in the art, there is still need for continuing improvement. One concern is that the tumbling action of the potato pieces should be such that there is as little breakage of the potato pieces as possible. Another concern is that the movement of the potato pieces be such as to have as much uniformity of cooking as possible (i.e., that substantially all surface portions are cooked with sufficient crispness and that adequate heat is imparted to each piece).
Another consideration is the venting of the fumes which result from the cooking of the potato pieces. Generally the potato pieces are precooked and then frozen. In the precooking, oil is used so that there is a residual amount of oil on the surfaces of the potato pieces. When the potatoes are heated by hot air, some of the more volatile elements of the surface oil vaporize, with some going through partial combustion. If these smoke-like gaseous products are permitted to accumulate in the oven chamber, when the oven is opened, these can enter into the ambient atmosphere, making a smoke-filled kitchen. Therefore the proper handling of the gaseous accumulation from the fries can be a problem.
In view of the foregoing, it is an object of the present invention to provide a food heating apparatus and method with a desirable balance of advantageous features to alleviate many of the problems associated with heating food, such as those recited above.